In recent years, it has been desirable to produce polymers bearing orthoester functional groups. Ethylenically unsaturated cyclic orthoesters have been produced according to a method set forth in U.S. patent application Ser. No. 07/645,179, filed Jan. 24, 1991 now U.S. Pat. No. 5,171,866, however, the commercial production of these monomers presents some difficulties. For example, the reaction of hydroxy orthoester with acryloyl chloride in methylene chloride as solvent and triethylamine as an acid scavenger results in the formation of triethylammonium hydrochloride, a by-product that is difficult to remove. These ammonium salts can lead to homopolymerization of the starting hydroxy orthoester. These side reactions result in lower yields and acylated oligomers. The formation of the vinyl benzyl ethers in U.S. patent application Ser. No. 07/645,179 now U.S. Pat. No. 5,171,866 requires the use of solid sodium hydroxide. Difficulties in handling the solid sodium hydroxide and similar reagents are overcome with the method of the current invention.
The monomers obtained by the method of the current invention overcome the above-mentioned difficulties. Higher yields and improved purity of the monomers formed are a result of using a phase transfer catalysis method described in the present invention.